N-butylbenzenesulphonamide

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2001

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EU Method C.4-C (Determination of the "Ready" Biodegradability - Carbon Dioxide Evolution Test)

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

sewage, predominantly domestic (adaptation not specified)

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): activated sludge was freshly obtained from a municipal sewage treatment plant: 'Waterschap de Maaskant, 's-Hertogenbosch, the Netherlands'
- Laboratory culture:
- Method of cultivation: The sludge was kept under continuous aeration until further treatment.
- Storage conditions:
- Storage length: 28 days (last CO2-measurement on the 29th day).
- Preparation of inoculum for exposure: Mineral components, Milli-RO water (ca. 80% total volume) and inoculum (0.8% final volume) were added to each bottle. This mixture was aerated with CO2-free air overnight to purge the system of CO2.

- Concentration of sludge:
- Initial cell/biomass concentration: From the supernatant of the sludge the heterotrophic microbial colony count was determined to be 3020 cell/ml.
- Water filtered: no
- Type and size of filter used, if any: /
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure):
- Laboratory culture:
- Method of cultivation:
- Storage conditions:
- Storage length:
- Preparation of inoculum for exposure:
- Pretreatment: allowed to settle for 30 minutes and decanted
- Concentration of sludge:
- Initial cell/biomass concentration:
- Water filtered: yes/no
- Type and size of filter used, if any:

Duration of test (contact time):

28 d

Initial conc.:

21.5 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium: Mineral components (stock solutions of mineral components:
a)8.5g KH2PO4/21.75g K2HPO4/67.20g Na2HPO4.12H2O/0.5g NH4Cl in 1l milli-q
b) 22.5g MgSO4.7H2O IN 1l milli-q
c) 36.4 g CaCl2.2H2O in 1l milli-q
d) 0.25g FeCl3.6H2O in 1l milli-q)
, milli-RO water (ca. 80% total volume) and inoculum (0.8% final volume) were added to each bottle.
- Additional substrate:
- Solubilising agent (type and concentration if used):
- Test temperature: 20-23°c
- pH: 7.6
- pH adjusted: no
- CEC (meq/100 g):
- Aeration of dilution water: no data
- Suspended solids concentration: 6.5 g/l in the concentrated sludge
- Continuous darkness: yes/no: no data
- Other:


TEST SYSTEM
- Culturing apparatus: The test was started by flushing CO2-free air through the solution at a rate of approximately 1-2 bubbles per second (ca. 30-100 ml/min).
- Number of culture flasks/concentration: Test suspension: containing test substance and inoculum (2 bottles)
Inoculum blank: containing only inoculum (2 bottles)
Positive control: containing reference substance (ca. 40 mg/l sodium acetate, TOC=12mg/l)
and inoculum (1 bottle)
Toxicity control: containing test substance, reference substance and inoculum (1 bottle).
- Method used to create aerobic conditions: a mixture of oxygen (21%) and nitrogen( 79%) was led trough a bottle,containing 0.5-1litre 0.0125 M Ba(OH)2 solution to trap co2 which might be present in small amounts. The co2-free air was sparged through the scrubbing solutions at aerate of approximately 1-2 bubbles per second( ca 30-100ml/min).
- Method used to create anaerobic conditions:
- Measuring equipment: Titration with 0.05M standardized HCl.
- Test performed in closed vessels due to significant volatility of test substance:
- Test performed in open system: 3 CO2-absorbers (bottles filled with 100ml 0.0125M Ba(OH)2) were connected in series to the exit air line of each test bottle.
- Details of trap for CO2 and volatile organics if used: A mixture of oxygen (21%) and nitrogen (79%) was led through a bottle, containing 0.5-1 l 0.0125 M Ba(OH)2 solution to trap CO2 which might be present in small amounts. The CO2-free air was sparged through the scrubbing solutions at a rate of approximately 1-2 bubbles per second (ca. 30-100 ml/min).
- Other:


SAMPLING
- Sampling frequency: titrations were made every second or third day during the first 10 days and thereafter at least every 5th day until the 28th day.
- Sampling method: each time the CO2-absorber nearest to the test bottle was removed for titration; each of the remaining two absorbers was moved one position in the direction of the test bottle. A new CO2-absorber was placed at the far end of the series.
- Sterility check if applicable: no data
- Sample storage before analysis: no data

- Other:


CONTROL AND BLANK SYSTEM
- Inoculum blank: containing only inoculum
- Abiotic sterile control: /
- Toxicity control: containing test substance, reference substance and inoculum
- Other:


STATISTICAL METHODS:
TEST CONDITIONS
- Composition of medium:
- Additional substrate:
- Solubilising agent (type and concentration if used):
- Test temperature:
- pH:
- pH adjusted: yes/no
- CEC (meq/100 g):
- Aeration of dilution water:
- Suspended solids concentration:
- Continuous darkness: yes/no
- Other:


TEST SYSTEM
- Culturing apparatus:
- Number of culture flasks/concentration:
- Method used to create aerobic conditions:
- Method used to create anaerobic conditions:
- Measuring equipment:
- Test performed in closed vessels due to significant volatility of test substance:
- Test performed in open system:
- Details of trap for CO2 and volatile organics if used:three co2 absorbers (bottles filled with 100 ml 0.0125 M ba(oh)2 were connected in series to the exit air line of each test bottle.
- Other:


SAMPLING
- Sampling frequency:
- Sampling method:
- Sterility check if applicable:
- Sample storage before analysis: no data
- Other:


CONTROL AND BLANK SYSTEM
- Inoculum blank:
- Abiotic sterile control:
- Toxicity control:
- Other:


STATISTICAL METHODS:

Reference substance:

acetic acid, sodium salt

Test performance:

The first step in calculating the amount of CO2-produced is to correct for background (endogenous) CO2-production relative to the total expected CO2-production based on the total carbon content of the amount of test material present in the test bottles. They were plotted versus time together with the relative degradation of the positive control.
A figure of more than 10% degradation was considered as significant.

Parameter:

% degradation (CO2 evolution)

Value:

ca. 12 - ca. 23

Sampling time:

28 d

Remarks on result:

other: average degradation was 18%

Details on results:

The results of the biodegradation test were considered to be valid when:
- the total CO2-evolution in the inoculum blank at the end of the test did not normally exceed 40 mg/l. If values greater than 70 mg CO2/l were obtained, the data and experimental technique should be examined critically
For the calculation of the total CO2-evolution in the inoculum blank the volume of HCl needed for the titration of the remaining Ba(OH)2 of the inoculum blanks and for fresh Ba(OH)2 was used.
- The absolute difference between the duplicate values of %-degradation of the test substance at the plateau, at the end of the test or at the end of the 10-day window, as appropriate, was less than 20.
- The percentage degradation of the reference substance reached the level for ready biodegrability (60%) by 14 days.

Because of the stringency of the method, low values of biodegradation do not necessarily mean that the test substance will not be biodegradable under environmental conditions. It rather indicates more work will be necessary to establish biodegradability.

Results with reference substance:

The positive control contained 80.4 mg sodium acetate (ThCO2 = 1.07 mg CO2/mg) resulting in a theoretical CO2-production following complete degradation of 86.0 mg / 2l.
The positive control substance was degraded at least 60% within 8 days.

Validity criteria fulfilled:

yes

Remarks:

Since all criteria for acceptability of the test were met, this study was considered to be valid.

Interpretation of results:

not readily biodegradable

Conclusions:

BBSA was not readily biodegradable under the conditions of the modified Sturm test presently performed.

Executive summary:

The biodegradation of BBSA in water was determined in a 28day ready biodegradability test with carbon dioxide evolution (modified sturm test). The substance was biodegraded for 12-23%. The substance is not ready biodegradable under the standard test conditions.

Description of key information

BBSA iss not readily biodegradable under the conditions of the modified Sturm test presently performed.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Type of water:

freshwater

Additional information

The biodegradation of BBSA in water was determined in a 28day-ready' biodegradability test with carbon dioxide evolution (modified sturm test). The substance was biodegraded for 12-23%, hence the substance is not ready biodegradable under the standard test conditions.